Welcome!

API Journal Authors: William Schmarzo, Rishi Bhargava, Pat Romanski, Elizabeth White, Kevin Benedict

Related Topics: Microsoft Cloud

Microsoft Cloud: Blog Feed Post

Windows Phone 7 Series Developer Experience

I’m excited about seeing what apps will get built now

imageToday at Mix10, Microsoft released the developer tools for Windows Phone 7 Series.  I’m excited about seeing what apps will get built now that there is general availability of the Windows Phone dev tools.  That’s general availability, as in for everyone!

Charlie Kindel (if you aren’t, you really should follow him) was nice enough to get me access to the tools about 3 weeks ago, despite the fact that he and his team have had plenty on their plate since going public with WP7.  I have spent some time in the last few winks building and tinkering.

A little background on my dev skills.  I can write basic applications, and have been known to favor Python when trying out new ideas.  I have dabbled a bit with our ASP.NET MVC (MVC v2 just released – way to go guys!!) and taught myself enough C# to be dangerous.  What coding I do, I do for fun and in my free time.  I call it my nocturnal nerdiness, and have been logging some of my projects using the n00bnotes tag.  Prior to 3 weeks ago, I had never written one line of Silverlight (or WPF for that matter) code, nor any XAML.  I was really excited to have the opportunity to build apps for this mobile platform, as I once tried to get along with iPhone development, and while it’s clear that Apple has created tools that developers seem to love, I couldn’t get along with ObjectiveC.  That’s a me issue, and not a statement about ObjectiveC.  I get along famously with Python, but me and Ruby are not friends.  That’s just the way my brain works.

imageWith that as a preamble, I wanted to share what I have created in just the last 3 weeks, working largely in what spare time I could find when not doing my day job or dealing with an recalcitrant 8 month old girl who refuses to sleep.  The main thing I want people to take away from this is that it in incredibly easy to built apps for Windows Phone 7.  If I can figure it out, anyone can.  The team has delivered a great development experience built on top of Visual Studio Express.  When you fire up the development environment, everything you need is there and you are ready to go.  It was a pretty painless experience to get the environment up and running, and it includes templates for Silverlight apps as well as XNA games.  While I have only been able to deploy to an actual phone once, the emulator felt like a software version of the phone.

Over the next few days of Mix10, I am going to put up a few posts about my experiences with the development tools, highlighting some of the blockers I hit, how I solved them, and for some of them, how I should have solved them, which I eventually fixed during code refactoring.

In the meantime, I wanted to share a link to the current version of the code.  This is my FriendLinks application, built for Windows Phone 7.  You will need the development tools in order to open, edit view.  The only disclaimer I make is that the code works.  Not all of it is pretty, and in some places I haven’t gone back to fix things I fixed elsewhere (i.e. walking XML for Bit.ly versus for Twitter).

This specific post is about some of the things that gave me the biggest problems in getting started.  The app that I built is pretty simple.  It’s meant to allow you to connect to Twitter, pull down your friend timeline, and parse the timeline looking for URLs sent by people you follow.  I use Twitter for content discovery, and this is my ultimate time waster app.  When you click on a link the listbox, some additional calls are made via the Bit.ly API, and the TweetMeme API, to get additional information like the number of retweets that article has, the title of the page referenced and the number of clicks as tracked by Bit.ly.

Making Async Calls to Web Services
Wow, what a huge pain this was for me to figure out.  When you do some web searching about how to connect to web services in C#, you will invariably find yourself staring at content about WebClient class.  I couldn’t make this work for me, and now that I am 3 weeks into it, I can’t remember what the specific issue was.  Something about Twitter not doing Basic Auth correctly, and needing to set the username and password in the header, necessitating the use of NetwrokCredentials.

In any event, I had to use the HttpWebRequest.  This is where things got challenging for me, since I had never done any async programming in C# or Silverlight.  [Apologies for the wonky formatting in the code samples, but I have a narrow blog and the style isn’t doing auto wrap]

public void GetStatuses()
{
    NetworkCredential nc = new NetworkCredential { UserName =
                          _username, Password = _password };

    string url = http://twitter.com/statuses/friends_timeline.xml?
                               + "count=" + _count + (_sinceID > 0 ?
                               "&since_id=" + _sinceID : "");
    System.Net.HttpWebRequest request =
                              (HttpWebRequest)HttpWebRequest.Create(url);
    request.Method = "GET";

    if (_username != null && _password != null)
    {
        request.Credentials = nc;
    }

    IAsyncResult token = request.BeginGetResponse(
                                  new AsyncCallback(GetStatusesCallBack),
                                  request);

}

Sorting out how to correctly get the async call done, and then set up the callback, was where I completely threw a rod.  Basically, you need to set up a web request to happen on its own thread, and then you need to assign a delegate function to process the response.  Figuring out how to do this took me 2 days, mostly because I didn’t know what questions to ask, or what terms to use when searching online, and in this specific case, only code that I did discover was useless for me because I was trying to learn something new and didn’t understand the samples I found.

Looking at the call, you may notice that I am using the REST API from Twitter, and setting the since_id and count variables to ensure that I am getting the data that I want.  This is so I can reuse this function to make subsequent calls while the app is running and only get the new tweets.  Twitter makes things pretty easy to get the data you want.

Here’s how you handle the async callback function to actually issue the HTTP request and process the data which comes back:

public void GetStatusesCallBack(IAsyncResult result)
{
    bool foundNewSinceID = false;

    try
    {

        WebResponse response = ((HttpWebRequest)result.AsyncState)
                                       .EndGetResponse(result);
        StreamReader reader = new StreamReader(response
                                       .GetResponseStream());
        string responseString = reader.ReadToEnd();

[note – this is a code snippet, and won’t work without closing that try{} and having an associated catch block]  What you end up with in the responseString is well formatted XML returned from Twitter.  Once I understood how to make these async calls, I was able to write any number of functions which handled getting data from other web services.

XML Processing
Oh man, what a complete cluster this was for me.  The Twitter API is well documented, and so I figured it would be pretty easy to parse the XML.  Unfortunately, I didn’t know what was available to me in Silverlight on Windows Phone 7 Series, so I started by asking Bing.

First things first, especially for those who are not well versed in Silverlight or Visual Studio.  If you want to parse XML, do yourself a huge favor and add a reference (“Project/Add Reference”) to System.Xml.Linq in your project.  Do that first.  With that, you can use XDocument.  Do it not, and you will have code that looks like this (focus on the while loop at the bottom):

public void GetStatusesCallBack(IAsyncResult result)
{
    string _name = null;
    string _status = null;
    long _tweetID = 0;

    bool foundNewSinceID = false;

    //need to set header for the sinceid and num replies
    try
    {
        WebResponse response = ((HttpWebRequest)result
                                    .AsyncState).EndGetResponse(result);
        StreamReader reader = new StreamReader(response
                                    .GetResponseStream());
        string responseString = reader.ReadToEnd();

        XmlReader xreader = XmlReader.Create(new
                                    StringReader(responseString));

        while (xreader.Read())
        {
            if (xreader.NodeType == XmlNodeType.Element
                           && xreader.Name == "text")
            {
                _status = CheckForLinks(xreader.ReadInnerXml());
            }

            if (xreader.NodeType == XmlNodeType.Element
                            && xreader.Name == "name")
            {
                _name = xreader.ReadInnerXml();
            }

Let’s talk about what’s going on here.  It turns out that if you ask Bing “.net read XML,” you will get posts and articles that talk about how to use XmlReader.  The first 10 links that come back all seem to point to this as a pattern for reading XML in .NET.  Not knowing what I was doing, I figured that this was the way to do it.  And so I set about building the code that would read XML and check for certain elements along the way.

This is not the right way to do this.  Absolutely, unequivocally not the right way.  As in, please, please, please don’t put yourself through this.  Never mind that if you get back poorly formed XML you have problems.  Or that sometimes the reader just decides not to work correctly.  Or you get some weird data back, and you throw an exception, which is non-deterministic to find because the bug only surfaced when Dave McClure posted something strange in his stream.  Oh, and the fact that Twitter use an “id” both for users and status, which makes the stream read a bit strange and easy to get the wrong value for statusID or userID.  Or that you end up with an unwieldy set of IF statements to parse your XML.  So to recap, don’t read XML this way.  Bad.  Very bad.

The right way to do things is to put the resposeString into an XDocument, and then perform a LINQ query against it.  You gain access to the XDocument via System.Xml.Linq, which is why I suggested adding that as a reference to your project.

public void GetStatusesCallBack(IAsyncResult result)
{
    bool foundNewSinceID = false;

    try
    {

        WebResponse response = ((HttpWebRequest)result
                                        .AsyncState).EndGetResponse(result);
        StreamReader reader = new StreamReader(response
                                        .GetResponseStream());
        string responseString = reader.ReadToEnd();

        XDocument twitterXML = XDocument.Parse(responseString);

        var twitObjs = from x in twitterXML.Descendants("status")
                      select new
        {
            tweetId = x.Element("id").Value,
            text = x.Element("text").Value,
            name = x.Element("user").Element("name").Value,
            profile_image_url = x.Element("user")
                                        .Element("profile_image_url").Value,
            userId = x.Element("user").Element("id").Value
        };

Isn’t that just so much prettier?  I had used LINQ before, but it was to access SQL objects, and for whatever reason I didn’t think to use LINQ to XML.  Shame on me.  n00bnotes hall of fame for sure.

Exceptions on the UI Thread
This one is very simple to understand and fix once you know what is going on, but a complete pain if you don’t understand why.  The “why” is that there is one UI thread in Silverlight.  If you want to update anything that is UI related, and your code isn’t being executed by the UI (for example, a delegate callback function), then you need to get that code onto the UI thread.  This is very, very simple to do, but I didn’t know how to ask the question to get the answer, and so it took me a little while to find the answer.

Dispatcher.BeginInvoke(() =>
{
    //these are some basic UI changes that you can make once on the UI thread
    grdTweets.Visibility = System.Windows.Visibility.Collapsed;
    grdLogin.Visibility = System.Windows.Visibility.Visible;

    txtPassword.Password = String.Empty;
    twitHelp.SetUserPass(txtUsername.Text, txtPassword.Password);

});

The lambda function off the Dispatcher is how you get your UI updating code onto the UI thread.  Just put your code in between the {} and you are all good.

My next post will talk about how I built out the listbox, which is the main piece of UI functionality, and the fun and interesting discovery process on how to use data binding.  I now love data binding.  A couple of days ago I hated it with a passion, but mostly because my code was wrong, I didn’t understand exactly what I was doing – more like just enough to sort of make things work, but not quite right enough that I noticed, and didn’t know how to debug.  So much fun. :)

More Stories By Brandon Watson

Brandon Watson is Director for Windows Phone 7. He specifically focuses on developers and the developer platform. He rejoined Microsoft in 2008 after nearly a decade on Wall Street and running successful start-ups. He has both an engineering degree and an economics degree from the University of Pennsylvania, as well as an MBA from The Wharton School of Business, and blogs at www.manyniches.com.

@ThingsExpo Stories
Why do your mobile transformations need to happen today? Mobile is the strategy that enterprise transformation centers on to drive customer engagement. In his general session at @ThingsExpo, Roger Woods, Director, Mobile Product & Strategy – Adobe Marketing Cloud, covered key IoT and mobile trends that are forcing mobile transformation, key components of a solid mobile strategy and explored how brands are effectively driving mobile change throughout the enterprise.
With so much going on in this space you could be forgiven for thinking you were always working with yesterday’s technologies. So much change, so quickly. What do you do if you have to build a solution from the ground up that is expected to live in the field for at least 5-10 years? This is the challenge we faced when we looked to refresh our existing 10-year-old custom hardware stack to measure the fullness of trash cans and compactors.
The emerging Internet of Everything creates tremendous new opportunities for customer engagement and business model innovation. However, enterprises must overcome a number of critical challenges to bring these new solutions to market. In his session at @ThingsExpo, Michael Martin, CTO/CIO at nfrastructure, outlined these key challenges and recommended approaches for overcoming them to achieve speed and agility in the design, development and implementation of Internet of Everything solutions wi...
Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is expected in the amount of information being processed, managed, analyzed, and acted upon by enterprise IT. This amazing is not part of some distant future - it is happening today. One report shows a 650% increase in enterprise data by 2020. Other estimates are even higher....
Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more business becomes digital the more stakeholders are interested in this data including how it relates to business. Some of these people have never used a monitoring tool before. They have a question on their mind like “How is my application doing” but no id...
Smart Cities are here to stay, but for their promise to be delivered, the data they produce must not be put in new siloes. In his session at @ThingsExpo, Mathias Herberts, Co-founder and CTO of Cityzen Data, will deep dive into best practices that will ensure a successful smart city journey.
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
Identity is in everything and customers are looking to their providers to ensure the security of their identities, transactions and data. With the increased reliance on cloud-based services, service providers must build security and trust into their offerings, adding value to customers and improving the user experience. Making identity, security and privacy easy for customers provides a unique advantage over the competition.
SYS-CON Events announced today that 910Telecom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Housed in the classic Denver Gas & Electric Building, 910 15th St., 910Telecom is a carrier-neutral telecom hotel located in the heart of Denver. Adjacent to CenturyLink, AT&T, and Denver Main, 910Telecom offers connectivity to all major carriers, Internet service providers, Internet backbones and ...
Almost two-thirds of companies either have or soon will have IoT as the backbone of their business in 2016. However, IoT is far more complex than most firms expected. How can you not get trapped in the pitfalls? In his session at @ThingsExpo, Tony Shan, a renowned visionary and thought leader, will introduce a holistic method of IoTification, which is the process of IoTifying the existing technology and business models to adopt and leverage IoT. He will drill down to the components in this fra...
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devices - comp...
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, will discuss the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
There is growing need for data-driven applications and the need for digital platforms to build these apps. In his session at 19th Cloud Expo, Muddu Sudhakar, VP and GM of Security & IoT at Splunk, will cover different PaaS solutions and Big Data platforms that are available to build applications. In addition, AI and machine learning are creating new requirements that developers need in the building of next-gen apps. The next-generation digital platforms have some of the past platform needs a...
19th Cloud Expo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterpri...
SYS-CON Events announced today Telecom Reseller has been named “Media Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
Pulzze Systems was happy to participate in such a premier event and thankful to be receiving the winning investment and global network support from G-Startup Worldwide. It is an exciting time for Pulzze to showcase the effectiveness of innovative technologies and enable them to make the world smarter and better. The reputable contest is held to identify promising startups around the globe that are assured to change the world through their innovative products and disruptive technologies. There w...
The 19th International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Digital Transformation, Microservices and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportuni...
I wanted to gather all of my Internet of Things (IOT) blogs into a single blog (that I could later use with my University of San Francisco (USF) Big Data “MBA” course). However as I started to pull these blogs together, I realized that my IOT discussion lacked a vision; it lacked an end point towards which an organization could drive their IOT envisioning, proof of value, app dev, data engineering and data science efforts. And I think that the IOT end point is really quite simple…
Personalization has long been the holy grail of marketing. Simply stated, communicate the most relevant offer to the right person and you will increase sales. To achieve this, you must understand the individual. Consequently, digital marketers developed many ways to gather and leverage customer information to deliver targeted experiences. In his session at @ThingsExpo, Lou Casal, Founder and Principal Consultant at Practicala, discussed how the Internet of Things (IoT) has accelerated our abil...
Is the ongoing quest for agility in the data center forcing you to evaluate how to be a part of infrastructure automation efforts? As organizations evolve toward bimodal IT operations, they are embracing new service delivery models and leveraging virtualization to increase infrastructure agility. Therefore, the network must evolve in parallel to become equally agile. Read this essential piece of Gartner research for recommendations on achieving greater agility.